Response from 'database.php' is have correct, there are numbers, not zeroes. Checked in Firebug.

I use ext-all.css, ext-base.js, ext-all.js given by ExtJs 3.3.1
Author used ExtJs 2.0.2 and gives his version of : ext-all.css, ext-base.js, ext-all.js (when i used that i had just blanks, not even zeroes)

1. Are you sure those fields are integers? Try using type:'auto' for the fields (you don't care about their field types anyway).
2. 'id' for both Store and JsonReader are deprecated. Use 'storeId' for Ext.data.Store and 'idProperty' for JsonReader.
3. Your type:'date' fields should have dateFormat, so they don't rely on the browser date format which is dependent on the locale.

they MUST be small, because in JsonReader result You have small
... {"0":"1","idpresident":"1","1":"1","idparty":"1","2":"George","firstname":"George","3":"Washington","lastname":"Washington","4":"1789-04-30","tookoffice":"04\/30\/1789","5":"1797-03-04","leftoffice":"03\/04\/1797","6":"135246.32","income":"135246.32","7":"1","8":"No Party","name":"No Party"} ...